This invention relates to a control of a torque converter clutch and more particularly to a system for regulating the application of the clutch to control undesirable driveline torque disturbances.
Introduced as an efficiency increasing device, the torque converter clutch is a fluid operated friction device engageable to couple the impeller (input) and turbine (output) of a hydraulic torque converter. In the usual application, the clutch is either fully released to permit hydrodynamic coupling between the engine and transmission gearset or fully engaged to permit direct mechanical coupling therebetween. An unfortunate aspect of full converter clutch engagement is that the engine torque perturbations or torsionals normally absorbed by the torque converter are passed directly through the clutch to the remainder of the vehicle drivetrain and vehicle structure and may produce annoying pulsations and undesirable fore-aft surging, commonly referred to as chuggle, if not properly damped. This factor operates to restrict the usage of the torque converter clutch to specified vehicle operating conditions for which most annoying effects are minimized. However, certain vehicle operating conditions prone to these disturbances may not be recognizable by conventional torque converter clutch control.